Electrically conducting bonding connection

ABSTRACT

An electrically conducting bonding connection (B) is produced between an electronic circuit (S) arranged on an electrically conducting support plate ( 1 ) and the support plate ( 1 ) by providing a hole ( 4, 5 ), into which an electrically conducting bonding element ( 2 ) with a bondable surface ( 3 ) is pressed in such a way that the support plate ( 1 ) and the bonding element ( 2 ) enter into an electrically conducting and frictional connection; the bonding connection is subsequently produced with the bonding element ( 2 ).

BACKGROUND OF THE INVENTION

[0001] The invention relates to an electrically conducting bondingconnection between an electronic circuit arranged on an electricallyconducting support plate and the support plate.

[0002] To ensure better stability or better heat removal, electroniccircuits are often arranged on metallic, electrically conducting supportplates.

[0003] From the electronic circuit, built up for example on a printedcircuit board or ceramic board, electrically conducting connections, forexample ground connections, to the metallic, electrically conductingsupport plate must be produced. Since support plates are generallyproduced from aluminum in a casting process, they are coated with anelectrically poorly conducting casting skin.

[0004] Until now, electrically conducting connections between theelectric circuit and the support plate have been produced by means ofbonding connections or by drilling threads into the support plate andattaching cables and cable lugs on it by means of screws.

[0005] Bonding connections are in this case usually produced by means ofthick aluminum wire. In this case, the surface of the support plate (forexample elevations created in the course of the casting process) must beprepared by machining shortly before the bonding operation, with theelectronic circuit already mounted, for example by milling, since abonding connection between aluminum wire and a casting skin is notpossible because it represents a connection which is mechanically andelectrically very poor.

[0006] Such a connection is very complex to produce, requiresconsiderable space and entails the risk of soiling (metal scobs causedby the milling work). A connection of this type cannot be produced byautomatic machines alone. Further, manual processing steps are required.

SUMMARY OF THE INVENTION

[0007] The invention is based on the object of producing an electricallyconducting connection between an electronic circuit and an electricallyconducting support plate with much lower space requirement and lowercosts by automatic machines alone, without further human action.

[0008] This object is achieved according to the invention by anelectrically conducting bonding connection between an electronic circuitarranged on an electrically conducting support plate and the supportplate, comprising a hole at the point of the support plate at which abonding connection is to be produced, an electrically conducting bondingelement with a bondable surface being pressed into the hole, wherein thesupport plate and the bonding element enter into an electricallyconducting and frictional connection, and whereby subsequently thebonding connection is produced.

[0009] A method for manufacturing an electrically conducting bondingconnection between an electronic circuit arranged on an electricallyconducting support plate and the support plate, comprises the steps of:

[0010] providing a hole at the point of the support plat at which abonding connection is to be produced,

[0011] pressing an electrically conducting bonding element with abondable surface into said hole, whereby the support plate and thebonding element enter into an electrically conducting and frictionalconnection, and whereby subsequently the bonding connection is produced.

[0012] Another embodiment of the present invention is a heat sinkcomprising an electrically conducting bonding connection between anelectronic circuit arranged on said heat sink wherein the heat sink isan electrically conducting support plate, a hole at the point of thesupport plate at which a bonding connection is to be produced, and anelectrically conducting bonding element with a bondable surface beingpressed into the hole, wherein the support plate and the bonding elemententer into an electrically conducting and frictional connection, andwhereby subsequently the bonding connection is produced.

[0013] This envisages providing holes or blind holes at the points ofthe support plate at which a bonding connection is to be produced, saidholes being cast already in the course of the casting operation orsubsequently drilled by automatic machines, and metallic bondingelements which have good electrical conduction and bond well are thenpressed into said holes by means of an automatic machine and enter intoa nonpositive connection with the support plate. The advantage ofdrilling is that an electronic circuit has not been mounted at thisstage and the support plate can be cleaned and freed of drilling scobsbefore mounting the electronic circuit.

[0014] One particular advantage of the invention is that the materialcomposition and bonding surface of the bonding elements can be freelychosen and can consequently be optimized for the connection to thesupport plate and for the bonding process. For example, the bondingelements may consist of cold-rolled aluminum or of nickel or have anickel-plated or gold-plated bonding surface.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] An exemplary embodiment according to the invention is describedin more detail below on the basis of a drawing, in which:

[0016]FIG. 1 shows a plan view of a support plate with an electroniccircuit mounted on it,

[0017]FIG. 2 shows a plan view and section of a bonding connection, and

[0018]FIG. 3 shows a section through a bonding connection with a blindhole.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019]FIG. 1 shows a plan view of a support plate 1, on which there ismounted an electronic circuit S, which itself may be arranged forexample on a printed circuit board. The electronic circuit S isconnected to the support plate by means of two bonding connections B(ground connections).

[0020]FIG. 2 shows in cross section and in a plan view a support plate 1with a through-hole 4, into which a bonding element 2, which is squarein plan view and is for example made of aluminum or has a gold-platedbonding surface 3, is pressed.

[0021] The bonding element may also be formed as a regular hexagon oroctagon in plan view. However, especially if it is created in the courseof the casting process, it is also possible for the hole to be a regularrectangle, hexagon or octagon in cross section and the bonding elementto be round.

[0022]FIG. 3 shows a support plate 1 in cross section, similar to FIG. 2but with the difference that the bonding element 2 is now pressed into ablind hole 5 instead of into a through-hole 4.

[0023] To produce the bonding connections, the support plate 1 is passedalong an automatic production line. If it has no holes 4, 5 preparedduring the casting operation, they are drilled in a first automaticstation and the support plate is subsequently automatically cleaned(otherwise it is possible to dispense with these operations).Subsequently, the bonding elements 2 are automatically pressed into theholes 4 or 5 provided and the electronic circuit S is mounted. Thebonding connections can subsequently be produced by an automatic bondingmachine.

[0024] All the operations mentioned can be carried out automatically,without intermediate manual steps.

1. An electrically conducting bonding connection between an electroniccircuit arranged on an electrically conducting support plate and thesupport plate, comprising a hole at the point of the support plate atwhich a bonding connection is to be produced, an electrically conductingbonding element with a bondable surface being pressed into said hole,wherein the support plate and the bonding element enter into anelectrically conducting and frictional connection, and wherebysubsequently the bonding connection is produced.
 2. The bondingconnection as claimed in claim 1, wherein the hole is made during thecasting operation of the support plate.
 3. The bonding connection asclaimed in claim 1, wherein the hole is drilled into the support plateand wherein the support plate is subsequently cleaned.
 4. The bondingconnection as claimed in claim 1, wherein the hole is a blind hole. 5.The bonding connection as claimed in claim 2, wherein the hole is formedas a regular rectangle, hexagon or octagon in plan view and the bondingelement is round.
 6. The bonding connection as claimed in claim 1,wherein the bonding element is formed as a regular rectangle, hexagon oroctagon in plan view.
 7. The bonding connection as claimed in claim 4,wherein the bonding element is formed as a regular rectangle, hexagon oroctagon in plan view.
 8. The bonding connection as claimed in claim 1,wherein the bonding element consists of aluminum.
 9. The bondingconnection as claimed in claim 1, wherein the bonding element consistsof nickel.
 10. The bonding connection as claimed in claim 1, wherein thebonding element has a nickel-plated bonding surface.
 11. The bondingconnection as claimed in claim 1, wherein the bonding element has agold-plated bonding surface.
 12. A method for manufacturing anelectrically conducting bonding connection between an electronic circuitarranged on an electrically conducting support plate and the supportplate, comprising the steps of: providing a hole at the point of thesupport plat at which a bonding connection is to be produced, pressingan electrically conducting bonding element with a bondable surface intosaid hole, whereby the support plate and the bonding element enter intoan electrically conducting and frictional connection, and wherebysubsequently the bonding connection is produced.
 13. Method as claimedin claim 12, wherein the hole is made during the casting operation ofthe support plate.
 14. Method as claimed in claim 12, wherein the holeis drilled into the support plate and wherein the support plate issubsequently cleaned.
 15. Method as claimed in claim 12, wherein thehole is a blind hole.
 16. Method as claimed in claim 13, wherein thehole is formed as a regular rectangle, hexagon or octagon in plan viewand the bonding element is round.
 17. Method as claimed in claim 12,wherein the bonding element is formed as a regular rectangle, hexagon oroctagon in plan view.
 18. Method as claimed in claim 12, wherein thebonding element is selected from the group of aluminum and nickel. 19.The bonding connection as claimed in claim 12, wherein the bondingelement has a surface selected from the group of nickel-plated bondingsurface and gold-plated bonding surface.
 20. A heat sink comprising: anelectrically conducting bonding connection between an electronic circuitarranged on said heat sink wherein the heat sink is an electricallyconducting support plate, a hole at the point of the support plate atwhich a bonding connection is to be produced, an electrically conductingbonding element with a bondable surface being pressed into said hole,wherein the support plate and the bonding element enter into anelectrically conducting and frictional connection, and wherebysubsequently the bonding connection is produced.